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Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells.

Akhtar MJ, Alhadlaq HA, Alshamsan A, Majeed Khan MA, Ahamed M - Sci Rep (2015)

Bottom Line: Characterization study confirmed the formation of single phase of Al(x)Zn(1-x)O nanocrystals with the size range of 33-55 nm.The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml.Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 &caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway.

View Article: PubMed Central - PubMed

Affiliation: King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451, Saudi Arabia.

ABSTRACT
We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of Al(x)Zn(1-x)O nanocrystals with the size range of 33-55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 &caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved.

No MeSH data available.


Related in: MedlinePlus

(A) UV-visible absorption spectra of pure and Al-doped ZnO nanoparticles. (B) Shifting of Fermi level due to transfer of electrons from valence band to conduction band. (C) (αhν)2vs photon energy plots of the corresponding sample used to determine their optical band gap energy.
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f3: (A) UV-visible absorption spectra of pure and Al-doped ZnO nanoparticles. (B) Shifting of Fermi level due to transfer of electrons from valence band to conduction band. (C) (αhν)2vs photon energy plots of the corresponding sample used to determine their optical band gap energy.

Mentions: The electronic structure of pure and Al-doped ZnO nanoparticles was characterized by the band gap, which was essentially the energy interval between valence band and conduction band, each of which has a high density of states. We calculated the electronic band gap of undoped and Al-doped ZnO nanoparticles because of their critical role in ROS mediated cytotoxicity. Figure 3A shows the absorbance spectra of undoped and Al-doped ZnO nanoparticles. A strong absorption peak appears at 314 nm for Al-doped ZnO nanoparticles, which is significantly blue shifted corresponding to pure ZnO nanoparticles peak (351 nm). The blue shift is attributed to the Burstein-Moss effect24. This leads to motion of Fermi level towards conduction band due to an increase in electron concentrations from Al ions (Fig. 3B). In general, Fermi level is situated at the center of the band gap. Shifting of Fermi level depends on the type of semiconductor. Al ions (n-type semicondutor) doping increases the conductivity of the intrinsic semiconductor by adding electron energy levels near the conduction band. The electron in these energy levels can be easily excited into the conduction band (Fig. 3B).


Aluminum doping tunes band gap energy level as well as oxidative stress-mediated cytotoxicity of ZnO nanoparticles in MCF-7 cells.

Akhtar MJ, Alhadlaq HA, Alshamsan A, Majeed Khan MA, Ahamed M - Sci Rep (2015)

(A) UV-visible absorption spectra of pure and Al-doped ZnO nanoparticles. (B) Shifting of Fermi level due to transfer of electrons from valence band to conduction band. (C) (αhν)2vs photon energy plots of the corresponding sample used to determine their optical band gap energy.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561961&req=5

f3: (A) UV-visible absorption spectra of pure and Al-doped ZnO nanoparticles. (B) Shifting of Fermi level due to transfer of electrons from valence band to conduction band. (C) (αhν)2vs photon energy plots of the corresponding sample used to determine their optical band gap energy.
Mentions: The electronic structure of pure and Al-doped ZnO nanoparticles was characterized by the band gap, which was essentially the energy interval between valence band and conduction band, each of which has a high density of states. We calculated the electronic band gap of undoped and Al-doped ZnO nanoparticles because of their critical role in ROS mediated cytotoxicity. Figure 3A shows the absorbance spectra of undoped and Al-doped ZnO nanoparticles. A strong absorption peak appears at 314 nm for Al-doped ZnO nanoparticles, which is significantly blue shifted corresponding to pure ZnO nanoparticles peak (351 nm). The blue shift is attributed to the Burstein-Moss effect24. This leads to motion of Fermi level towards conduction band due to an increase in electron concentrations from Al ions (Fig. 3B). In general, Fermi level is situated at the center of the band gap. Shifting of Fermi level depends on the type of semiconductor. Al ions (n-type semicondutor) doping increases the conductivity of the intrinsic semiconductor by adding electron energy levels near the conduction band. The electron in these energy levels can be easily excited into the conduction band (Fig. 3B).

Bottom Line: Characterization study confirmed the formation of single phase of Al(x)Zn(1-x)O nanocrystals with the size range of 33-55 nm.The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml.Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 &caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway.

View Article: PubMed Central - PubMed

Affiliation: King Abdullah Institute for Nanotechnology, King Saud University, Riyadh 11451, Saudi Arabia.

ABSTRACT
We investigated whether Aluminum (Al) doping tunes band gap energy level as well as selective cytotoxicity of ZnO nanoparticles in human breast cancer cells (MCF-7). Pure and Al-doped ZnO nanoparticles were prepared by a simple sol-gel method. Characterization study confirmed the formation of single phase of Al(x)Zn(1-x)O nanocrystals with the size range of 33-55 nm. Al-doping increased the band gap energy of ZnO nanoparticles (from 3.51 eV for pure to 3.87 eV for Al-doped ZnO). Al-doping also enhanced the cytotoxicity and oxidative stress response of ZnO nanoparticles in MCF-7 cells. The IC50 for undoped ZnO nanoparticles was 44 μg/ml while for the Al-doped ZnO counterparts was 31 μg/ml. Up-regulation of apoptotic genes (e.g. p53, bax/bcl2 ratio, caspase-3 &caspase-9) along with loss of mitochondrial membrane potential suggested that Al-doped ZnO nanoparticles induced apoptosis in MCF-7 cells through mitochondrial pathway. Importantly, Al-doping did not change the benign nature of ZnO nanoparticles towards normal cells suggesting that Al-doping improves the selective cytotoxicity of ZnO nanoparticles toward MCF-7 cells without affecting the normal cells. Our results indicated a novel approach through which the inherent selective cytotoxicity of ZnO nanoparticles against cancer cells can be further improved.

No MeSH data available.


Related in: MedlinePlus